Causes of Depression

Introduction to causes of depression

Have you ever wondered what causes clinical depression? Perhaps you have been diagnosed with major depression, and that's made you question why some people get depressed while others don't.

Depression is an extremely complex disease. It occurs for a variety of reasons. Some people experience depression during a serious medical illness. Others may have depression with life changes such as a move or the death of a loved one. Still others have a family history of depression. Those who do may experience depression and feel overwhelmed with sadness and loneliness for no known reason.

What Are the Main Causes of Depression?

There are a number of factors that may increase the chance of depression, including the following:

  • Abuse. Past physical, sexual, or emotional abuse can cause depression later in life.
  • Certain medications. For example, some drugs used to treat high blood pressure, such as beta-blockers or reserpine, can increase your risk of depression.
  • Conflict. Depression may result from personal conflicts or disputes with family members or friends.
  • Death or a loss. Sadness or grief from the death or loss of a loved one, though natural, can also increase the risk of depression.
  • Genetics. A family history of depression may increase the risk. It's thought that depression is passed genetically from one generation to the next. The exact way this happens, though, is not known.
  • Major events. Even good events such as starting a new job, graduating, or getting married can lead to depression. So can moving, losing a job or income, getting divorced, or retiring.
  • Other personal problems. Problems such as social isolation due to other mental illnesses or being cast out of a family or social group can lead to depression.
  • Serious illnesses. Sometimes depression co-exists with a major illness or is a reaction to the illness.
  • Substance abuse. Nearly 30% of people with substance abuse problems also have major or clinical depression.

How Is Biology Related to Depression?

Researchers have noted differences in the brains of people who are depressed as compared to people who are not. For instance, the hippocampus, a small part of the brain that is vital to the storage of memories, appears to be smaller in people with a history of depression than in those who've never been depressed. A smaller hippocampus has fewer serotonin receptors. Serotonin is a calming brain chemical known as a neurotransmitter that allows communication between nerves in the brain and the body. It's also thought that the neurotransmitter norepinephrine may be involved in depression.

Scientists do not know why the hippocampus is smaller in those with depression. Some researchers have found that the stress hormone cortisol is produced in excess in depressed people. These investigators believe that cortisol has a toxic or poisonous effect on the hippocampus. Some experts theorize that depressed people are simply born with a smaller hippocampus and are therefore inclined to suffer from depression.

One thing is certain -- depression is a complex illness with many contributing factors. The latest scans and studies of brain chemistry that show the effects of antidepressants help broaden our understanding of the biochemical processes involved in depression. As scientists gain a better understanding of the cause(s) of depression, health professionals will be able to make better "tailored" diagnoses and, in turn, prescribe more effective treatment plans.



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